const string field vs "typed" string

Question

i have a little function that goes like this:

void Bar(string s)
{
*/ do somthing with the string here.*/
}

void Foo()
{
    Bar("Hello");
}

if i look at the IL output, it gives me the following:

.method private hidebysig instance void Foo() cil managed
{
    .maxstack 8
    L_0000: ldarg.0 
    L_0001: ldstr "Hello"
    L_0006: call instance void TestApp.MainWindow::Bar(string)
    L_000b: ret 
}

now i thought i'd replace it with a const string field for it.

const string str= "Hello";
void Foo()
{
    Bar(str);
}

that translates TO THE EXACT SAME IL snippet.

now my question is which one to use?

Foo("Hello"); or Foo(cHello);

Thank you for your help!

--------------EDIT-------------------
To be more specific, i use this for Logging purposes to add a prefix to a message: AND it would only appear once in code!

so it looks more like this:

void LogDebug(string msg)
{
    Log("[DEBUG]", msg)
}
void Log(string pre, string msg)
{
    // generates an output in form of
    // pre + msg
}

:)

Answer 1

The answer should be obvious: since the IL is the same, use whatever works best based on purely source-code considerations.

In general, this means going with the const string in order to not have a magic value appear in your Foo method. If the constant is used just once this might not sound very convincing, but if there is even a possibility of using it more than once in the future then DRY is pretty much a shotgun argument.

Update:

In this specific case (debugging output, constant is guaranteed to be used only once) I don't think that a constant provides any value. I 'd hardcode the string literal.